Russian President Vladimir Putin said he must respond to the massive attack by Ukrainian drones on Russian air bases.
The news was made by US President Donald Trump after a telephone conversation between the two presidents.
Russian officials declined to confirm the report Wednesday night, but Moscow had previously said military options were “on the table.”
Trump said in a post on social media that the phone call, which lasted more than an hour, “will not lead to a quick peace” between Russia and Ukraine.